1. Field of the Invention
The present invention relates generally to F-F (front engine-front wheel drive) vehicles and more specifically to a structure therefor which absorbs the impact energy resulting from a frontal collision of the vehicle in such a manner as to minimize the degree by which the forward bulkhead is deformed.
2. Description of the Prior Art
In a known arrangement such as illustrated in FIGS. 1 and 2 of the drawings, a side member 1 has been disposed longitudinally along each side of an engine compartment 2. Each of the side members 1 has a box-section which gradually flares out as the side member extends from the front of the vehicle toward the rear thereof. The aft end of the side member is connected to both the dash panel, which forms part of the forward bulkhead 3, and the floor panel 4 of the vehicle cabin.
In this type of arrangement in order to allow for the provision of a laterally disposed engine, particularly wherein the engine is of the type where the transmission 7 is fixed to the engine proper at one end thereof, the side member 1 must be located at a relatively high position within the vehicle as compared with a conventional F-R (front engine-rear wheel drive) vehicle, to prevent mutual interference therebetween. This of course induces a rather large offset "L1" between the side member 1 and each corresponding extension member 8 which is fixed to the lower surface of the floor panel 4 inboard of the side sills 9 (shown in phantom). The extension members 8 (only one is shown) are of course preferably fixed to the lower surface of the floor panel 4 so as to not detract from the "leg room" of the cabin and are connected to a forward cross member 10 spanning between the two very rigid side sills 9.
In an effort to strengthen the connection between the side member 1 and the extension member 8 & forward bulkhead 3 and provide the desired amount of vehicle body rigidity, reinforcements 11 have been included in the structure in order to compensate for the large offset inherent therein.
However, this arrangement has suffered from a number of drawbacks which include production and assembly complexity. Viz., the many and various members constituting the side and reinforcement members 11, etc., must be very complexly shaped so as to minimize the waste when pressing and stamping the panels and provide the desired structural strength; which in turn renders the docking of the members together during assembly both difficult and time consuming.
Further, and more importantly, this arrangement has suffered in that during a frontal collision such as a "head on" collision or the like, the side member 1 instead of desirably buckling uniformly along its length (and thus absorbing the impact energy) and subsequently directing the impact shock through the very rigid extension member/floor panel/cross member/side sill construction, tends to (as shown in chain line) markedly buckle upwardly at the point of least structural strength (Viz., in the vicinity of Q1). This in combination with the rather large offset required in F-F vehicles produces a rather large moment of force which in turn markedly buckles the extension member/floor panel construction about a point Q2 in the direction indicated by the arrow. The result of the buckling of the vehicle structure about these two points subsequently tends to pull the engine 6 and transmission 7 upwardly within the engine compartment 2 allowing the unit to be driven against the relatively weak forward bulkhead 3 increasing the deformation of the vehicle cabin 5. This latter said deformation is of course highly undesirable as the limbs and body of the vehicle occupants are highly endangered by same.